Perinatal morbidity among women with a previous caesarean delivery (PRISMA trial): a cluster-randomised trial.

BACKGROUND: Women with a previous caesarean delivery face a difficult choice in their next pregnancy: planning another caesarean or attempting vaginal delivery, both of which are associated with potential maternal and perinatal complications. This trial aimed to assess whether a multifaceted intervention, which promoted person-centred decision making and best practices, would reduce the risk of major perinatal morbidity among women with one previous caesarean delivery. METHODS: We conducted an open, multicentre, cluster-randomised, controlled trial of a multifaceted 2-year intervention in 40 hospitals in Quebec among women with one previous caesarean delivery, in which hospitals were the units of randomisation and women the units of analysis. Randomisation was stratified according to level of care, using blocked randomisation. Hospitals were randomly assigned (1:1) to the intervention group (implementation of best practices and provision of tools that aimed to support decision making about mode of delivery, including an estimation of the probability of vaginal delivery and an ultrasound estimation of the risk of uterine rupture), or the control group (no intervention). The primary outcome was a composite risk of major perinatal morbidity. This trial was registered with ISRCTN, ISRCTN15346559. FINDINGS: 21 281 eligible women delivered during the study period, from April 1, 2016 to Dec 13, 2019 (10 514 in the intervention group and 10 767 in the control group). None were lost to follow-up. There was a significant reduction in the rate of major perinatal morbidity from the baseline period to the intervention period in the intervention group as compared with the control group (adjusted odds ratio [OR] for incremental change over time, 0·72 [95% CI 0·52-0·99]; p=0·042; adjusted risk difference -1·2% [95% CI -2·0 to -0·1]). Major maternal morbidity was significantly reduced in the intervention group as compared with the control group (adjusted OR 0·54 [95% CI 0·33-0·89]; p=0·016). Minor perinatal and maternal morbidity, caesarean delivery, and uterine rupture rates did not differ significantly between groups. INTERPRETATION: A multifaceted intervention supporting women in their choice of mode of delivery and promoting best practices resulted in a significant reduction in rates of major perinatal and maternal morbidity, without an increase in the rate of caesarean or uterine rupture. FUNDING: Canadian Institutes of Health Research (CIHR, MOP-142448).

Measurement of Lower Uterine Segment Thickness to Detect Uterine Scar Defect: Comparison of Transabdominal and Transvaginal Ultrasound.

OBJECTIVES: Lower uterine segment (LUS) thickness measurement using transabdominal ultrasound (TA-US), transvaginal ultrasound (TV-US), or the combination of both methods can detect scar defect in women with prior cesarean. We aimed to compare the sensitivity of three approaches. METHODS: Women with prior cesarean underwent LUS thickness measurement at 34-38 weeks' gestation. Among those who underwent repeat cesarean before labor, we compared the accuracy of TA-US, TV-US, and the thinner of the two measurements (the "combined measurement") for uterine scar dehiscence using the area under the curve (AUC) of receiver operating curves with their 95% confidence intervals (CI). We calculated the sensitivity and specificity of the three approaches using a cut-off of 2.3 mm based on prior literature. RESULTS: We included 747 participants. The mean LUS thickness was greater with TA-US (3.8 ± 1.6 mm) compared with TV-US (3.5 ± 1.9 mm) or the combined measurement (3.2 ± 1.5 mm; P < .001). The AUC was 78% (95% CI: 69%-87%), 85% (95% CI: 79%-91%), and 88% (95% CI: 82%-93%), respectively (all with P < .001). The AUC difference between TA-US and the combined measurement was not significant (P = .057). A LUS below 2.3 mm would have predicted 9 (45%) of the 20 cases of uterine scar dehiscence using TA-US, 17 (85%) using TV-US, and 18 (90%) using the combined measurement (P < .01). CONCLUSION: The choice of ultrasound approach influences the measurement of the LUS thickness. The combination of the TA-US and TV-US seems to be superior for the detection of uterine dehiscence.

Laser micromachining of periodic surface radius change on the optical fiber circumference.

In this paper, we are showing that holes and marking spots with sizes that are comparable to the wavelength of a CO2 laser at λ=10.6 µm can be achieved reproducibly on a conventional optical fiber SMF28 when it is positioned at the focal point. Some theory on Gaussian beam propagation is briefly reviewed and readily applied to drill a fiber on its axis near the focal point. As the fiber was moved from the focal point, it was found that some features, such as ridges along the fiber circumference, were also micromachined by the laser. It was demonstrated that the fabrication of surface nanoaxial photonic fibers, long-pitch grating fibers, and pump laser strippers can be envisaged on a conventional SMF28 with a cladding diameter of 125 µm.

Defining cylindrical space optical resonators through supported mode properties: inverse numerical process.

Faraday's and Ampere's laws are converted to matrix operator form and rearranged such that the unknown relative permittivity and relative permeability tensors can be determined. The material and geometry of cylindrically symmetric optical resonator structures are determined through the electric and magnetic field component profiles and complex angular frequency of a proposed localized state. This differs from the usual utilization of the electromagnetic wave equations, solving for states given the material properties and geometry. Thus the technique presented here is an inverse numerical process. The theoretical expressions are provided based on a Fourier-Bessel numerical approach which is highly suitable for cylindrical geometry resonators. Without loss of the generality of the technique, examples of resonant structure determination are presented for non-magnetic and diagonal relative permittivity tensor. Axial field propagation is included to demonstrate the design capabilities related to optical fiber and photonic crystal fiber structures.

Single versus double-layer uterine closure at cesarean: impact on lower uterine segment thickness at next pregnancy.

BACKGROUND: Uterine rupture is a potential life-threatening complication during a trial of labor after cesarean delivery. Single-layer closure of the uterus at cesarean delivery has been associated with an increased risk of uterine rupture compared with double-layer closure. Lower uterine segment thickness measurement by ultrasound has been used to evaluate the quality of the uterine scar after cesarean delivery and is associated with the risk of uterine rupture. OBJECTIVE: To estimate the impact of previous uterine closure on lower uterine segment thickness. STUDY DESIGN: Women with a previous single low-transverse cesarean delivery were recruited at 34-38 weeks' gestation. Transabdominal and transvaginal ultrasound evaluation of the lower uterine segment thickness was performed by a sonographer blinded to clinical data. Previous operative reports were reviewed to obtain the type of previous uterine closure. Third-trimester lower uterine segment thickness at the next pregnancy was compared according to the number of layers sutured and according to the type of thread for uterine closure, using weighted mean differences and multivariate logistic regression analyses. RESULTS: Of 1613 women recruited, with operative reports available, 495 (31%) had a single-layer and 1118 (69%) had a double-layer closure. The mean third-trimester lower uterine segment thickness was 3.3 ± 1.3 mm and the proportion with lower uterine segment thickness <2.0 mm was 10.5%. Double-layer closure of the uterus was associated with a thicker lower uterine segment than single-layer closure (weighted mean difference: 0.11 mm; 95% confidence interval [CI], 0.02 to 0.21 mm). In multivariate logistic regression analyses, a double-layer closure also was associated with a reduced risk of lower uterine segment thickness <2.0 mm (odd ratio [OR], 0.68; 95% CI, 0.51 to 0.90). Compared with synthetic thread, the use of catgut for uterine closure had no significant impact on third-trimester lower uterine segment thickness (WMD: -0.10 mm; 95% CI, -0.22 to 0.02 mm) or on the risk of lower uterine segment thickness <2.0 mm (OR, 0.95; 95% CI, 0.67 to 1.33). Finally, double-layer closure was associated with a reduced risk of uterine scar defect (RR, 0.32; 95% CI, 0.17 to 0.61) at birth. CONCLUSION: Compared with single-layer closure, a double-layer closure of the uterus at previous cesarean delivery is associated with a thicker third-trimester lower uterine segment and a reduced risk of lower uterine segment thickness <2.0 mm in the next pregnancy. The type of thread for uterine closure has no significant impact on lower uterine segment thickness.

Lower uterine segment thickness to prevent uterine rupture and adverse perinatal outcomes: a multicenter prospective study.

BACKGROUND: Choice of delivery route after previous cesarean delivery can be difficult because both trial of labor after cesarean delivery and elective repeat cesarean delivery are associated with risks. The major risk that is associated with trial of labor after cesarean delivery is uterine rupture that requires emergency laparotomy. OBJECTIVE: This study aimed to estimate the occurrence of uterine rupture during trial of labor after cesarean delivery when lower uterine segment thickness measurement is included in the decision-making process about the route of delivery. STUDY DESIGN: In 4 tertiary-care centers, we prospectively recruited women between 34 and 38 weeks of gestation who were contemplating a vaginal birth after a previous single low-transverse cesarean delivery. Lower uterine segment thickness was measured by ultrasound imaging and integrated in the decision of delivery route. According to lower uterine segment thickness, women were classified in 3 risk categories for uterine rupture: high risk (<2.0 mm), intermediate risk (2.0-2.4 mm), and low risk (≥2.5 mm). Our primary outcome was symptomatic uterine rupture, which was defined as requiring urgent laparotomy. We calculated that 942 women who were undergoing a trial of labor after cesarean delivery should be included to be able to show a risk of uterine rupture <0.8%. RESULTS: We recruited 1856 women, of whom 1849 (99%) had a complete follow-up data. Lower uterine segment thickness was <2.0 mm in 194 women (11%), 2.0-2.4 mm in 217 women (12%), and ≥2.5 mm in 1438 women (78%). Rate of trial of labor was 9%, 42%, and 61% in the 3 categories, respectively (P<.0001). Of 984 trials of labor, there were no symptomatic uterine ruptures, which is a rate that was lower than the 0.8% expected rate (P=.0001). CONCLUSION: The inclusion of lower uterine segment thickness measurement in the decision of the route of delivery allows a low risk of uterine rupture during trial of labor after cesarean delivery.

Labor Dystocia and the Risk of Uterine Rupture in Women with Prior Cesarean.

Objective The objective of this study was to evaluate the association between labor dystocia and uterine rupture. Methods We performed a secondary analysis of a multicenter case-control study that included women with single, prior, low-transverse cesarean section who experienced complete uterine rupture during a trial of labor (TOL). For each case, three women who underwent a TOL without uterine rupture were selected as controls. Data were collected on cervical dilatations from admission to delivery. We evaluated the relationship between uterine rupture and labor dystocia according to several criteria, including the World Health Organization's (WHO's) partogram. Results Data were available for 90 cases and 260 controls. Compared with the controls, uterine rupture was associated with less cervical dilatation on admission, slower cervical dilatation in the first stage of labor and longer second stage of labor (all with p < 0.05). Performing cesarean when the labor curve crossed the ACTION line of WHO's partogram or when the second stage was greater than 2 hours could have (1) prevented up to 56% of uterine rupture and (2) reduced the duration of labor in 57% of women with failed TOL. Conclusion Labor dystocia is a significant risk factor for uterine rupture. Labor progression should be assessed regularly in women with prior cesarean.

Dielectric profile segmentation used to reduce computation effort of the Fourier-Bessel mode solving technique.

The Fourier-Bessel space conversion of Maxwell's wave equations into an eigenvalue formulation is a useful numerical tool for computing the steady states of cylindrically symmetric dielectric structures. The relative dielectric profile, inverse (1/εr) present in wave equations, is split into a constant offset and corresponding spatially dependent residue and greatly reduces the matrix building time (and thus computation time) when alternate dielectric configurations are considered with identical spatial distributions. Such a process significantly speeds up the theoretical analysis of numerous optical designs, such as index of refraction sensors, hole infiltration sensors and resonator tuning. The theoretical steps involved are presented along with examples of the technique applied to the well-known Bragg resonator and central defect containing hexagonal array.

Spherical space Bessel-Legendre-Fourier localized modes solver for electromagnetic waves.

Maxwell's vector wave equations are solved for dielectric configurations that match the symmetry of a spherical computational domain. The electric or magnetic field components and the inverse of the dielectric profile are series expansion defined using basis functions composed of the lowest order spherical Bessel function, polar angle single index dependant Legendre polynomials and azimuthal complex exponential (BLF). The series expressions and non-traditional form of the basis functions result in an eigenvalue matrix formulation of Maxwell's equations that are relatively compact and accurately solvable on a desktop PC. The BLF matrix returns the frequencies and field profiles for steady states modes. The key steps leading to the matrix populating expressions are provided. The validity of the numerical technique is confirmed by comparing the results of computations to those published using complementary techniques.

Randomized controlled trial of physiotherapy for postpartum stress incontinence: 7-year follow-up.

OBJECTIVE: To estimate the long-term effect of intensive, 6-week physiotherapy programs, with and without deep abdominal muscle (TrA) training, on persistent postpartum stress urinary incontinence (SUI). METHODS: The study was a single-blind randomized controlled trial. Fifty-seven postnatal women with clinically demonstrated persistent SUI 3 months after delivery participated in 8 weeks of either pelvic floor muscle training (PFMT) (28) or PFMT with deep abdominal muscle training (PFMT + TrA) (29). Seven years post-treatment, 35 (61.4%) participants agreed to the follow-up; they were asked to complete a 20-min pad test and three incontinence-specific questionnaires with an assessor blinded to each participant's group assignment. RESULTS: Of the 35 (61.4%) who agreed to the follow-up: 26 (45.6%) took the 20-min pad test (12 PFMT and 14 PFMT + TrA) and 35 (61.4%) completed the questionnaires (18 PFMT and 17 PFMT + TrA). The baseline clinical characteristics of the follow-up and non-follow-up participants were not significantly different; nor did they differ between PFMT and PFMT + TrA participants enrolled in the follow-up study. At 7 years, the pad test scores for the PFMT group did not differ statistically from those of the PFMT + TrA group. When combining both treatment groups, a total of 14/26 (53%) follow-up participants were still continent according to the pad test. CONCLUSION: The addition of deep abdominal training does not appear to further improve the outcome of PFM training in the long term. However, benefits of physiotherapy for postpartum SUI, although not as pronounced as immediately after the initial intervention, is still present 7 years post-treatment.

Adverse obstetric outcomes in women with previous cesarean for dystocia in second stage of labor.

OBJECTIVE: To evaluate obstetric outcomes in women undergoing a trial of labor (TOL) after a previous cesarean for dystocia in second stage of labor. METHODS: A retrospective cohort study of women with one previous low transverse cesarean undergoing a first TOL was performed. Women with previous cesarean for dystocia in first stage and those with previous dystocia in second stage were compared with those with previous cesarean for nonrecurrent reasons (controls). Multivariable regressions analyses were performed. RESULTS: Of 1655 women, those with previous dystocia in second stage of labor (n = 204) had greater risks than controls (n = 880) to have an operative delivery [odds ratio (OR): 1.5; 95% confidence intervals (CI) 1.1 to 2.2], shoulder dystocia (OR: 2.9; 95% CI 1.1 to 8.0), and uterine rupture in the second stage of labor (OR: 4.9; 95% CI 1.1 to 23), and especially in case of fetal macrosomia (OR: 29.6; 95% CI 4.4 to 202). The median second stage of labor duration before uterine rupture was 2.5 hours (interquartile range: 1.5 to 3.2 hours) in these women. CONCLUSION: Previous cesarean for dystocia in the second stage of labor is associated with second-stage uterine rupture at next delivery, especially in cases of suspected fetal macrosomia and prolonged second stage of labor.

Fourier-Bessel analysis of localized states and photonic bandgaps in 12-fold photonic quasi-crystals.

A Fourier-Bessel (FB) basis is used to solve two-dimensional (2D) cylindrical Maxwell's equations for localized states within dielectric structures that possess rotational symmetry. The technique is used to determine the wavelengths and profiles of the stationary states supported by the structure and identify the bandgaps. 12-fold quasi-crystals for the TE and TM polarizations are analyzed. Since the FB approach with 2D photonic crystals in this fashion is new, the accuracy of the results is confirmed using finite-difference time-domain simulations.

Modal analysis and device considerations of thin high index dielectric overlay slab waveguides.

The effect of adding a thin high index dielectric overlay layer onto a 3-layer slab waveguide demonstrates several interesting features that can be exploited in integrated optical device configurations. A simple modal analysis is employed to examine the behavior of guided light launched from a 3-layer waveguide structure then coupled and propagated in the 4-layer overlay region. Modal properties typically overlooked in conventional slab waveguides are made use of in the design and theoretical analysis of an MMI device and optical index of refraction sensor. The optical structure presented here can form the backdrop waveguide design for more complex and active devices.

Impact of labor at prior cesarean on lower uterine segment thickness in subsequent pregnancy.

OBJECTIVE: The objective of the study was to identify the factors associated with sonographic lower uterine segment (LUS) thickness near term in women with prior low transverse cesarean. STUDY DESIGN: A prospective cohort study of women with a single prior low transverse cesarean was conducted. LUS thickness was quantified by transabdominal ultrasound with repeated transvaginal measurement when necessary. The thinnest measurement was considered as the dependent variable. Potential related factors were evaluated with nonparametric analyses and multivariate logistic regressions. RESULTS: Two hundred thirty-five women were recruited at a mean gestational age of 36.7 +/- 1.3 weeks. The full LUS was thicker in women who had their previous cesarean during the latent phase (2.8 mm; interquartile [IQ], 2.0-3.3 mm) or the active phase of labor (3.1 mm; IQ 2.5-3.9 mm) than in women with previous cesarean prior to labor (2.4 mm; IQ 2.0-3.2 mm). The association remained significant after adjustment for potential confounders. CONCLUSION: Presence of labor at previous cesarean is associated with a thicker LUS in a subsequent pregnancy.

[Measurement of the lower uterine segment: are we ready for a clinical application?]. / Mesure du segment inférieur utérin : sommes-nous prêts pour une application clinique ?

The measurement of the lower uterine segment (LUS) seems to be the best technique available to estimate the risk of uterine rupture, but there is a great heterogeneity in the techniques used. It appears necessary to standardize the interventions and their teaching prior to extending the use of the LUS measurement to clinical settings beyond well-defined research purposes.

Prediction of complete uterine rupture by sonographic evaluation of the lower uterine segment.

OBJECTIVE: The purpose of this study was to establish the validity of sonographic evaluation of lower uterine segment (LUS) thickness for complete uterine rupture. STUDY DESIGN: A prospective cohort study of women with previous cesarean delivery was conducted. LUS thickness (full thickness and myometrial thickness only) was measured between 35 and 38 weeks gestation, and the thinnest measurement was considered to be the dependent variable. Receiver operating curve analyses and logistic regression were used. RESULTS: Two hundred thirty-six women were included in the study. Nine uterine scar defects (3 cases of complete rupture during a trial of labor and 6 cases of dehiscence) were reported. Receiver operating curve analyses showed that full thickness of <2.3 mm was the optimal cutoff for the prediction of uterine rupture (3/33 vs 0/92; P = .02). Full thickness was also identified as an independent predictor of uterine scar defect (odds ratio, 4.66; 95% confidence interval, 1.04-20.91) CONCLUSION: Full LUS thickness of <2.3 mm is associated with a higher risk of complete uterine rupture.

Age at diagnosis of autism spectrum disorders in four regions of Canada.

OBJECTIVES: Early diagnosis of autism spectrum disorders ("autism") may lead to better treatment outcomes, reduces the stress parents experience when they do not understand the reasons for their child's behaviour, and empowers parents to make choices such as seeking genetic counseling. We examined the age at which Canadian children are diagnosed with autism, and analyzed whether there are geographic or temporal variations or differences by sex or diagnostic subtype. METHODS: As part of an autism surveillance program, in 2002/2003 we began collecting information on children with autism in Manitoba, Southeastern Ontario, Prince Edward Island, and Newfoundland and Labrador. For the analysis presented in this paper, we included children identified for our surveillance program who were diagnosed between 1997 and 2005 (n = 769). RESULTS: We found significant inter-regional differences in age at diagnosis, with Newfoundland and Labrador having the lowest median age at diagnosis (39.0 months) and Southeastern Ontario the highest (55.0 months). Diagnostic subtype was significantly associated with age at diagnosis in all regions. Southeastern Ontario was the only region where the overall age at diagnosis increased over time (p = 0.004), although in Manitoba the age at which children were diagnosed with PDD-NOS also increased significantly over the study period (p = 0.021). CONCLUSIONS: Our findings demonstrate that there are geographic differences and other sources of variation in the age at which Canadian children are diagnosed with autism. Further study is warranted to understand the factors contributing to these differences. Such research would inform best practices for early detection and timely access to treatment.

Absence of association of thrombophilia polymorphisms with intrauterine growth restriction.

BACKGROUND: Previous data have demonstrated associations between thrombophilia polymorphisms in pregnant women and an increased risk of intrauterine growth restriction in their offspring, but this finding remains uncertain. METHODS: We performed a hospital-based case-control study and a family-based study including 493 newborns with intrauterine growth restriction (defined by birth weight below the 10th percentile for gestational age and sex according to Canadian norms) and 472 controls (with birth weight at or above the 10th percentile). We determined the presence or absence in newborns and their parents of the following polymorphisms: methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, factor V Leiden G1691A, and prothrombin G20210A. Mothers were interviewed to obtain information on other risk factors for intrauterine growth restriction. RESULTS: The risk of intrauterine growth restriction was not increased among mothers carrying a polymorphism associated with thrombophilia. In the case-control study, the odds ratios associated with two copies of the variant, after adjustment for newborn genotype and other risk factors, were 1.55 for MTHFR C677T (95 percent confidence interval, 0.83 to 2.90) and 0.49 for MTHFR A1298C (95 percent confidence interval, 0.25 to 0.93); heterozygotes for factor V Leiden had an odds ratio of 1.18 (95 percent confidence interval, 0.54 to 2.55), and heterozygotes for prothrombin G20210A had an odds ratio of 0.92 (95 percent confidence interval, 0.36 to 2.35). These polymorphisms in the newborn were not associated with an increased risk. Newborns who were homozygous for the MTHFR C677T variant had a decreased risk of intrauterine growth restriction (odds ratio after adjustment for mother's genotype and other confounders, 0.52 [95 percent confidence interval, 0.29 to 0.94]). The results of the family-based study supported those of the case-control study. CONCLUSIONS: Our findings do not indicate that there are associations between maternal or newborn polymorphisms associated with thrombophilia and an increased risk of intrauterine growth restriction.

Mode localization and band-gap formation in defect-free photonic quasicrystals.

Defects in photonic crystals are local regions in which the translational symmetry is broken. The same definition can be applied to photonic quasicrystals except in this case the symmetry is the 2pi/n rotational symmetry, where n is the rotational fold number. In this context, if no such defects are present, the structure is called "defect-free". Even though photonic quasicrystal patterns can be defect-free, localized modes can still exist in such structures. These modes resemble those of a central potential that suggests that localization in photonic quasicrystals are actually "extended" modes of the rotational symmetry. A possible connection is suggested between these localized modes and short-range dependence of the photonic band gap (PBG). Such a connection implies a tight-binding description of PBG formation of photonic quasicrystals - making them more similar to electronic semiconductors than regular photonic crystals.

Mid-trimester genetic amniocentesis in twin pregnancy and the risk of fetal loss.

OBJECTIVE: To assess the rate of fetal losses in twin pregnancies undergoing genetic mid-trimester amniocentesis. METHODS: In the first part of this investigation, a retrospective cohort study compared a group of women . 32 years old with twin pregnancies who underwent amniocentesis with a similar group unexposed to amniocentesis. Data were compiled from January 1990 to March 2004 for patients from a single institution. Pregnancies complicated by twin-to-twin transfusion syndrome, monoamniotic twins, or lethal fetal anomalies, and those treated by fetal reduction were excluded. The primary outcome was the loss of one or both fetuses prior to 24 weeks' gestation. In the second part of the investigation, a systematic review of the literature and a meta-analysis were performed. RESULTS: In the first part of the study, data were collected for 132 women exposed to amniocentesis and 248 women not exposed to amniocentesis. There was no significant difference in the rate of fetal losses between the two groups (3.0% vs. 0.8%, P = 0.10). No losses occurred within four weeks of the procedure. In the second part of the investigation, four studies, including ours, were considered for a meta-analysis of 2026 women with twin pregnancies. Compared with women unexposed to the procedure, amniocentesis in women with twin pregnancies increased the risk of fetal losses prior to 20 to 24 weeks' gestation (odds ratio 2.42; 95% confidence intervals 1.24-4.74, P = 0.01) with an additional risk of one adverse outcome (1 or 2 fetal losses) for every 64 amniocenteses. CONCLUSION: Genetic mid-trimester amniocentesis in twin pregnancies is associated.